1890.] On the Development of the Tuotara. ].*>5 



that all the tuataras I had kept for the past year (twenty-nine ia 

 number) were males. This arose chiefly from the fact that males 

 are more easily obtained than females ; bat it is possible that oar 

 desire to obtain the largest, most vigorous, and fnlly adult animals 

 for breeding accounts in part for our having retained only males for 

 breeding purposes. 



On the occasion of this second visit I secured as many females as I 

 could, but found more difficulty in obtaining females than males, so 

 that I set a number of males at liberty as being superfluous. The 

 apparently greater abundance of the males is perhaps due to the 

 females seeking concealment more than the other sex ; at any rate, I 

 am led to suggest this from the observation of my tuataras kept in con- 

 finement. The instinct of concealment would, of course, be of special 

 value to a female laden with eggs. 



Notwithstanding that I now possessed a dozen pairs of tuataras, no 

 eggs were obtained the following summer. The lizards had been kept 

 in large houses and were well cared for, and appeared in good health, 

 but would not bpeed. Capitivity would seem to interfere with their 

 reproductive powers, an effect which would hardly be anticipated with 

 animals of so sluggish a nature. 



I could only refep their sterility in confinement to a change in some 

 of the conditions of life consequent on captivity, and endeavouring, 

 therefore, to make their surroundings approximate more closely to 

 the natural ones, I had still larger houses constructed, and extensive 

 runs on the open groand enclosed. 



It was not, however, till January, 1889, that eggs were obtained, 

 and even then some of them were infertile. Weary of the constant 

 watching of the lizards in previous summers, I took a short holiday 

 at the New Year, and during an absence of five or six days a female 

 lizard died, but was not noticed by the attendant in charge. On 

 my return I found that it' had contained twelve fully formed eggs ; 

 they had, however, begun to putrefy. A second female laid ten eggs, 

 which proved infertile. A third, which promised well, died from in- 

 ability to lay its- eggs. It" was closely watched, and dissected within 

 an hour of its death. The oviducts contained four and five eggs re- 

 spectively, fully formed and ready for laying. From these eggs were 

 obtained a number of embryos at various stages of development, from 

 a stage equal to a two days' chick up to a stage shortly before hatch- 

 ing. This year I hoped to obtain a further supply of embryos, but 

 only one female has laid, and her eggs were infertile. 



The eggs of the tuatara are oval in form, both ends being- of equal 

 diameter, and vary in length from 2'5 to 3'35 cm. The egg-shell is 

 probably much like that of other oviparous lizards, being tough, flexible, 

 and very elastic ; it contains a varying amount of carbonate of lime. 

 The eggs dry and shrivel with great readiness when exposed to the 



